Exploring the Impact of Genetic Variations on The Clinical Efficacy of Nalbuphine in Postoperative Pain Management

Anaesthesia induction will be done with propofol (2 mg/kg) nalbuphine (0.1mg/kg) and atracurium (0.6mg/kg) intravenously. Maintenance of anaesthesia will be achieved with oxygen (O2), nitrous oxide (N2O) in 1:2 ratio and isoflurane (0.8-1%). Intermittent top up of the study drug 1-2 ml boluses will be administered if either the patient's HR or BP increased to 20 % above baseline and when other causes of tachycardia and hypertension are excluded. Timing of analgesia will be recorded. Pain will be assessed for 24 hours postoperatively using verbal rating scale (VRS) with 0 = no pain and 10 = worst pain. Sedation will be assessed as 0=no sedation, 1= mild sedation, (eye-opening on verbal commands), 2= moderate sedation (eye-opening on painful stimulus), 3= deep sedation (not waking up on pain). All patients will be prescribed paracetamol one gram IV six hourly and nalbuphine 1-2 mg IV infusion in the first 24 hours post operatively.

5ml of blood samples by venipuncture will be obtained from the first 70 patients half an hour before extubation at the time of muscle closure. These blood samples will be processed for DNA analysis. Only the 15 samples where pain persisted despite nalbuphine administration, with a pain score remaining above 4, continuous use of rescue analgesia, or any documented opioid side effects (such as nausea, vomiting, or sedation), or the need for additional analgesia within 24 hours, will be sent for NGS analysis. These samples will undergo whole exome sequencing via NGS, based on patient parameters and pain scores, after being categorized as responders or non-responders to nalbuphine

Only the 15 samples will be sent for NGS based on patient parameters and pain scores after being categorized as responders or non-responders to nalbuphine